﻿Report 
  of 
  the 
  State 
  Geologist. 
  515 
  

  

  It 
  is 
  in 
  this 
  portion 
  of 
  the 
  ridge 
  that 
  the 
  principal 
  cement 
  

   quarries 
  of 
  Eondout 
  are 
  situated. 
  They 
  extend 
  continuously 
  along 
  

   the 
  eastern 
  slopes 
  to 
  the 
  lower 
  loop 
  in 
  the 
  Ulster 
  and 
  Delaware 
  rail- 
  

   way, 
  and 
  penetrate 
  far 
  down 
  the 
  dip 
  to 
  the 
  westward. 
  The 
  typical 
  

   structure 
  in 
  this 
  belt 
  is 
  shown 
  in 
  section 
  IV, 
  plate 
  4. 
  This 
  gives 
  

   place 
  northward 
  to 
  an 
  anticlinal, 
  shown 
  in 
  section 
  III. 
  This 
  

   begins 
  as 
  a 
  sharp, 
  somewhat 
  faulted 
  crumple 
  in 
  the 
  monocline, 
  

   which 
  rapidly 
  widens 
  and 
  pitches 
  downward 
  to 
  the 
  east 
  and 
  

   southeast. 
  The 
  cement 
  rock 
  was 
  mined 
  from 
  the 
  east-dipping 
  

   limb, 
  but 
  as 
  this 
  portion 
  of 
  the 
  mine 
  had 
  long 
  been 
  abandoned 
  

   and 
  there 
  are 
  no 
  surface 
  outcrops, 
  I 
  could 
  not 
  ascertain 
  the 
  pre- 
  

   cise 
  relations 
  northeastward. 
  The 
  anticlinal 
  gives 
  rise 
  to 
  a 
  

   bench 
  along 
  the 
  east 
  side 
  of 
  the 
  ridge, 
  over 
  which 
  the 
  upper 
  road 
  

   to 
  Kingston 
  passes 
  diagonally. 
  On 
  the 
  crest 
  of 
  this 
  bench 
  the 
  

   Tentaculite 
  beds 
  are 
  exposed, 
  lying 
  nearly 
  flat, 
  but 
  they 
  dip 
  

   steeply 
  down 
  its 
  eastern 
  slope 
  and 
  pitch 
  beneath 
  the 
  sand 
  and 
  

   clay 
  of 
  the 
  terrace. 
  JSTorth 
  of 
  the 
  road 
  the 
  bench 
  is 
  terminated 
  

   by 
  a 
  face 
  in 
  which 
  a 
  gentle 
  arch 
  of 
  the 
  Tentaculite 
  limestone 
  and 
  

   cement 
  beds 
  are 
  exposed. 
  The 
  cement 
  is 
  being 
  mined 
  from 
  this 
  

   face 
  in 
  a 
  series 
  of 
  galleries 
  extending 
  to 
  the 
  westward. 
  The 
  

   west 
  limb 
  of 
  the 
  anticlinal 
  is 
  gently 
  flexed 
  by 
  a 
  low, 
  local 
  syncli- 
  

   nal 
  which 
  is 
  irregular 
  in 
  strike 
  and 
  not 
  of 
  great 
  extent 
  southward. 
  

   The 
  northern 
  road 
  to 
  Kingston 
  crosses 
  the 
  ridge 
  in 
  a 
  partial 
  gap 
  

   in 
  this 
  vicinity, 
  and 
  the 
  variations 
  in 
  strike 
  are 
  very 
  noticeable 
  

   in 
  the 
  Pentamerus 
  beds 
  along 
  the 
  road 
  as 
  well 
  as 
  in 
  the 
  cement 
  

   beds 
  in 
  the 
  mine 
  below. 
  

  

  The 
  formations 
  constituting 
  the 
  ridge 
  in 
  the 
  vicinity 
  of 
  sec- 
  

   tions 
  III 
  and 
  IY, 
  on 
  plate 
  4, 
  are 
  the 
  Helderberg 
  limestones, 
  the 
  

   Oriskany 
  sandstone, 
  the 
  Salina 
  cement 
  series, 
  and 
  the 
  Hudson 
  

   river 
  sandstones. 
  Mather,* 
  Cook,f 
  Lindsley, 
  X 
  Dale§ 
  and 
  Davis 
  | 
  

   have 
  described 
  various 
  features 
  of 
  this 
  portion 
  of 
  the 
  region 
  and 
  

   their 
  statements 
  are 
  mainly 
  accordant. 
  The 
  fact 
  was 
  recognized 
  

   that 
  the 
  limestones 
  lie 
  unconformably 
  on 
  the 
  Hudson 
  river 
  sand- 
  

   stones, 
  and 
  this 
  feature 
  is 
  very 
  clearly 
  exposed 
  at 
  a 
  number 
  of 
  

  

  * 
  Loc. 
  cit. 
  

  

  t 
  Geology 
  of 
  New 
  Jersey, 
  1868, 
  p. 
  156. 
  

  

  t 
  A 
  study 
  of 
  the 
  rocks. 
  Poughkeepsie 
  Soc. 
  Nat. 
  Scl., 
  Proc., 
  vol. 
  2. 
  

  

  § 
  The 
  fault 
  at 
  Rondout. 
  Am. 
  Jour. 
  Sci., 
  3d 
  ser., 
  vol. 
  18, 
  1879, 
  pp. 
  293-295. 
  

  

  I 
  Nonconformity 
  at 
  Rondout. 
  Am. 
  Jour. 
  8ci., 
  3d 
  ser., 
  vol. 
  26, 
  1893, 
  pp. 
  389-395. 
  

  

  